Reflection-type video projection screen

ABSTRACT

A projection screen includes a substrate, a reflective layer having a first surface and an opposing second surface, and diffusion layer. The second surface of the reflective layer is attached (e.g., via an adhesive) to the substrate and the diffusion layer is attached (e.g., via an optically transparent adhesive) to the first surface of the reflective layer. The first surface of the reflective layer has an unpolished (e.g., matte) finish. The projection screen is preferably flexible and wound around a conventional roller to form a projection screen system. Alternatively, the projection screen may be attached to a rigid substrate. In one embodiment, the diffusion layer includes two surfaces, one of which is attached to the first surface of the reflective layer and the other of which is outward facing. At least the outward facing surface of the diffusion layer includes irregularities to achieve a desired screen directivity performance.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. application Ser.No. 10/719,356, which is a continuation-in-part of U.S. application Ser.No. 10/125,628 (now U.S. Pat. No. 6,724,529), and hereby claims priorityupon such co-pending application under 35 U.S.C. §120.

BACKGROUND OF THE INVENTION

This invention relates to reflection-type projection screens. Moreparticularly, the invention relates to reflection-type projectionscreens having excellent reflection directivity in the horizontal andvertical directions yet which produce a reflected image having superiorgain and contrast.

The desirability of producing reflection-type projection screens havinga wide angle of reflectivity with suitable contrast is well known. Insettings such as movie theaters and home viewing areas, the viewer isoften times positioned at a significant angle with respect to thedirection of the projected image from the projector, i.e. the directionof incident projected light. Therefore, the screen must have aneffective viewing angle greater than would be producible if a highlyreflective medium were used alone.

Numerous attempts have been made to remedy this problem. U.S. Pat. No.3,653,740 to Ogura (“the '740 Patent”) discloses a projection screenhaving a double rolled aluminum foil sheet attached to a support member,and a brushed resin film covering the foil as a protective coatingagainst scratching, fingerprints, etc. No mention is made of thebrushing techniques used or of the resulting surface characteristic ofthe resin film after it is brushed.

U.S. Pat. No. 6,144,491 to Orikasa (“the '491 Patent”) discloses areflection-type projection screen having a substrate, a light reflectinglayer made from a transparent resin in which flakes of alight-reflective material are dispersed, and a transparentlight-diffusing layer made from a transparent resin in which finecrystalline particles of calcite and a pigment are dispersed. The filmsof '491 Patent are complicated, expensive and particularly difficult toachieve.

U.S. Pat. No. 6,040,941 to Miwa (“the '941 Patent”) discloses areflection-type projection screen having a light-reflecting substratelaminated to a light-transmitting polymer layer having light absorptiveslits or “crazes” of regular directionality disposed therein. The slitsare filled with a light-absorbing substance such as a black pigment ordye.

U.S. Pat. No. 6,233,095 B1 to Niwa (“the '095 Patent”) discloses areflex-type screen comprised of a first layer formed integrally with aninner reflex layer on a surface of a substrate, and a second layerformed of a deflection film bonded to a surface of the first layer. Thescreen of the '095 Patent was developed to facilitate the use of screenswhich can be deflected, e.g. rolled up when not in use. Beads such asacrylic or silicon beads are applied to the substrate surface prior todeposition of a metal reflective layer, rendering the process ofattaching the metal reflective layer all the more complicated.

U.S. Pat. No. 5,456,967 to Nezu (“the '967 Patent”) discloses areflection-type screen of the type that can be wound up in a roll formand unwound as needed and comprises a substrate sheet to which islaminated a high-density light diffusion-reflection layer and atranslucent light diffusion layer including a soft vinyl chloride sheet,the translucent light diffusion layer having a surface provided with alight-diffusing fine uneven pattern.

U.S. Pat. No. 5,361,163 to Matsuda (“the '163 Patent”) discloses areflection-type projection screen comprising a dark plastic substrate, afibrous sheet of glass fibers, a white, opaque base material sheet and alight diffusing layer of a translucent plastic onto which a lustrouspigment or calcite powder is incorporated. An emboss is formed on theouter surface of the light diffusion layer. Light absorbing strips areprovided each at a position corresponding to a concave portion of theemboss on the surface of the base material sheet adjoining the lightdiffusing layer.

U.S. Pat. No. 5,148,309 to Yamada (“the '309 Patent”) discloses areflective type screen comprising a reflective surface layer, apolarizing plate layer in position in front of the reflective surfacelayer, and a diffusion layer located in front of the polarized platelayer, wherein the reflective surface layer, the polarizing plate layerand the diffusion layer are laminated together using an adhesive to forman integral structure. Additional embodiments are disclosed in the '309Patent, all of which require a polarizing layer, perhaps to accommodateexotic applications of projection images onto a screen.

U.S. Pat. No. 4,232,939 to Kikuchi (“the '939 Patent”) discloses atransparent base plate to which is attached on one side an aluminummirror surface and on the other side a diffusing specular layer of lowdiffusing performance. The diffusing performance of the diffusingspecular layer can be adjusted as desired while the reflectionperformance of the mirror surface is constant. The diffusing specularlayer is formed with a plurality of elongated columnar lenticles havingconvex surfaces facing the viewer. The curvature of the lenticles isdetermined by the distance between the screen and the viewers. The outerconvex surface of the lenticles is treated by sandblasting. Thelenticles are arranged in a vertically elongated pattern, whichsacrifices vertical directivity.

U.S. Pat. No. 4,201,449 to Campion (“the '449 Patent”) teaches a frontprojection screen having a substrate, a reflective aluminum ink coatingapplied to a surface of a substrate, and a protective coating,preferably of a clear acrylic having a gloss finish for the purpose ofprotecting the reflective film. The disclosure specifies that thecoating reduces somewhat the reflective efficiency of the screen.Therefore, the directionality of such a screen is likely to be extremelynarrow.

U.S. Pat. No. 4,190,320 to Ferro (“the '320 Patent”) teaches a frontprojection screen having two reflecting layers separated by a lighttransmissive layer, and a light-diffusing surface coating provided onthe frontmost reflecting layer. The screen forms an embossed patternacross its front surface.

U.S. Pat. No. 4,089,587 to Schudel (“the '587 Patent”) discloses aprojection screen having a film which is constructed of a partiallydeformable, resilient material. One surface of the film has incombination a random matte texture and a substantially unidirectionalstriated, i.e. grooved, texture. A layer of reflective material isdeposited on the above-mentioned surface of the film to provide a highgain, damage resistant reflective surface. The screen of the '587 Patentis intended to be of the double-coverture type, i.e. curved about atleast two axes so as to focus the reflected image in a confined area.Another embodiment of the '587 Patent discloses a flat screen.Striations are provided, usually vertically aligned to disburse thelight reflected off of the reflective film. The arrangement of thestriations or lenticles as vertical grooves limits the directionality tonearly a side-by-side viewing field and not top to bottom or diagonal.

SUMMARY OF THE INVENTION

It is therefore, an object of this invention to provide a frontprojection screen that overcomes the aforementioned disadvantages andshortcomings.

It is also an object of this invention to provide a front projectionscreen that provides the same directionality (i.e., directivity) alongvertical as well as horizontal axes relative to a normal line passingperpendicularly through the center of the projection screen.

It is a further object of this invention to provide a projection screenthat is simple and inexpensive to manufacture and light weight yet whichprovides directivity characteristics not heretofore experienced.

It is a further object of the present invention to provide an improveddirectivity projection screen that is flexible and capable of beingrolled around a roller to form a composite and optionally portableprojection screen system.

In accordance with these and other objects, the present invention isdirected to a projection screen comprised of a reflective filmlaminated, as by the use of adhesive, metal deposition, or otherwise aswill occur to those of skill in the art, to a light diffusing layer onone side and, on another side, as by adhesive, metal deposition, orother techniques known to those of skill in the art, to a substrate. Thesubstrate may be rigid or flexible, flat or curved.

The reflective film may be vacuum metalized silver or vacuum metalizedaluminum or any other film exhibiting a high coefficient ofreflectivity. The characteristics of the light diffusing layer can beadjusted depending upon the desired effect, intensity of projected imagelight, ambient conditions, etc. One form of the diffusing layer is anembossed film. One form of such embossed film contains a plurality ofconcavities embossed in the film that act as micro lenses. The surfacecharacteristics (e.g., concavities) associated with the light diffusinglayer can be formed by techniques such as hot roll stamping, ultraetching or the like. Another form of such embossed film contains aplurality of irregularities on at least one surface thereof. Suchirregularities are preferably in the form of a matte surface fabricatedby rolling or comparable techniques.

The reflective layer may be adhered to the substrate or to thesubstrate-facing inner surface of the light diffusing layer.

It can therefore be appreciated that one embodiment of the invention isto a projection screen comprising a substrate; a reflective layer havinga first surface and an opposing second surface, the second surface ofthe reflective layer being attached to the substrate, the first surfaceof the reflective layer having an unpolished finish; and a diffusionlayer attached to the first surface of the reflective layer.

These and other objects and features of the invention will be morereadily understood from a consideration of the following detaileddescription, taken with the accompanying drawings, in whichcorresponding parts are indicated by corresponding numerals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional, elevational, exploded view of a generalizedembodiment of the invention.

FIG. 2 is a cross-sectional, elevational, exploded view of analternative embodiment of the invention.

FIG. 3 is a perspective, partial cutaway, view of the alternativeembodiment shown in FIG. 2.

FIG. 4 is a perspective exploded partial cutaway view of the alternativeembodiment of FIGS. 2 and 3.

FIG. 5 is a flow diagram of the method of the invention.

FIG. 6 is a cross-sectional, elevational, exploded view of a projectionscreen in accordance with another alternative embodiment of the presentinvention.

FIG. 7 is a perspective, partial cutaway, view of the alternativeprojection screen shown in FIG. 6.

FIG. 8 is a perspective view of a projection screen system in accordancewith a further alternative embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, the screen of the first embodiment of theinvention is indicated by the reference numeral 10 and includes asubstrate 15, which may be planar or curved depending upon therequirements of the particular application, and which, in the preferredembodiment, is of the rigid foam core variety with plastic sheet panelson both sides for rigidity. Although the screen of this invention can beused for any front projected image, it is particularly suitable for usewith LCD projection or DLP and the like projection systems. Thesubstrate is commonly found in, and is preferably in, the thicknessrange of between ¼ inch and 2 inches. The thickness of the substrate 15is dictated by such parameters as strength requirements for a given sizeof screen, the environment in which the screen will be used, etc. Thesubstrate defines a forward-facing or front surface 17.

A reflective, preferably metalized, film layer 20 is included, whichdefines a forward facing, reflective, surface 22 and a rear surface 24adapted to be connected to or placed adjacent to, surface 17 ofsubstrate15.

A light diffusing layer 30 is employed which sandwiches the reflectivelayer 20 between light diffusing layer 30 and front surface 17 ofsubstrate 15. Layer 30 defines a forward facing surface 32 and a rearfacing surface 34. Rear surface 34 is disposed adjacent to forwardsurface 22 of reflective layer 20.

Reflective layer 20 may be adhered to rear surface 34 of light diffusinglayer 30 by any suitable means, such as metallic deposition or usingtransparent adhesive, etc. If an adhesive is used, it should be anoptically transparent formulated adhesive that is transparent to light.Reflective layer 20 may alternatively be applied to the rearward facingsurface 34 of light diffusing layer 30 or to forward facing surface 17of substrate 15 by vacuum metalization. The preferred materials whichconstitute layer 20 are silver or aluminum. Still further, reflectivelayer 20 may be a metal film such as aluminum, and may have a highpolished mirror finish, a matte finish or any other surface treatmentdeemed desirable by one of skill in the art.

The light diffusing layer 30 is preferably fabricated of a resin such aspolyethylene, polypropylene or other material which will permit lightenergy to enter through forward facing surface 32 and to be reflected byreflective layer 20 back through light diffusing layer 30 but in amanner which will increase the viewing angle of the reflected image suchthat the image can be seen from a wide angle relative to a line Irepresenting a projected image light ray or wave projected at screen 10.

The higher the angle of diffusion, the wider the angle of viewing thatwill be perceived by those watching the image reflected by the screen.Normally, increasing the angle of diffusion results in a decrease in theluminance of reflected light. The make-up and physical contouring oflight diffusing layer 30 is chosen so as to maximize the diffusion anglewhile also maximizing the luminance of reflected light. Simultaneously,the contrast of the reflected image should be kept as high as possiblefor greater picture clarity. An ideal range of thickness of lightdiffusing layer 30 is between 2-8 mils.

The ambient light characteristics, as well as the light intensity of theprojected image, dictate the particular characteristics chosen for thelight diffusing layer 30. Under conditions where less diffusion isrequired such as in a setting where the viewing angle does not need tobe as great, polyethylene can be used as a constituent of lightdiffusing layer 30. For viewing settings where a greater angle ofdiffusion is desired, polypropylene can be used as a constituent oflight diffusing layer 30. The forward surface 32, or the rearwardsurface 34, or both, of light diffusing layer 30 can be treated and/orcontoured as by random embossing, micro lensing, sandblasting or anyequivalent thereto indicated as reference number 35 in FIG. 1. Treatment35 effects the magnitude of diffusion of the reflected image exitinglight diffusing layer 30.

As seen in FIGS. 2-4, an alternative or second embodiment of theinvention comprises a front projection screen 40 in which a substrate45, which may be similar to that described in connection with FIG. 1, isprovided, and which defines a front surface 47. A reflective layer 50 isemployed, also as disclosed in connection with FIG. 1, including forwardfacing reflective surface 52. A light diffusing layer 60 is employed,which defines forward surface 62 and rear surface 64. In thisalternative embodiment, layer 60 defines a plurality of micro lenses M,which are, preferably, concavities in the shape of semi spheres, prisms,parabaloids, or any other raised structure which functions as a lens orprism with respect to light incident thereupon. Layer 50 may belaminated to inner surface 64 of light diffusing layer 60 (or to forwardfacing surface 47 of substrate 45) by a transparent adhesive (notshown), by vacuum deposition, or any other technique which will occur toone of skill in the art. Layer 50 may be made of any of the compositionsdiscussed in connection with layer 20 of FIG. 1. Micro lenses M may beformed in light diffusing layer 60 by ultra etching, embossing, hotstamp rolling, or any other forming technique which will yield smalllens-shaped concavities or solid embossed light-refracting elementstherein. Micro lenses M may also be formed in other shapes, such asmicro prisms, similar to those manufactured by Reflexsite Corporation.

The dimensions of the micro lenses such as a radius of curvature forcurved lenses M, or the height and slope of sides if micro prisms areused, can be varied to effect the diffusion properties of diffusionlayer 60. A larger radius of curvature, or a shallower slope,respectively, will yield smaller diffusion angles, and smaller radii ofcurvature, or steeper prism slopes, respectively will yield largerdiffusion angles. For a home projection television, a higher diffusionangle is preferred, while in a movie theater setting a lower diffusion,higher concentrated, light reflectivity could be tolerated.

The luminance of reflected light (i.e., gain) of reflective layers 20and 50 can be made lower for home television applications, while thesame characteristics of screens 10, 40, respectively, can be increasedfor the commercial (e.g., movie theater) application.

It is to be understood that the particular surface treatments and/orcontouring of light diffusing layers 30 and 60 herein can be broughtabout by any suitable means which will occur to one of skill in the art.The addition of protective films (not shown) over the outer surfaces 32,62 of light diffusing layers 30, 60, respectively, is also contemplatedto be within the scope of the invention, if desired.

Screens as disclosed herein are suitable for use in dark or fulldaylight conditions, and provide visual performance characteristics nothereto before known. It is to be understood that variations in materialsand dimensions are contemplated to be within the scope of this inventionwithout departing without the spirit hereof.

A method, depicted schematically in FIG. 5, is also disclosed forcreating the screen of this invention. The method comprises the stepsof: providing a suitable diffusion layer; forming micro lenses in thediffusion layer; depositing the reflective layer thereon; and mating thediffusion layer/reflective layer composite to the substrate. In thisway, very inexpensive yet high performance projection screens inconformance with the invention can be provided.

FIG. 6 is a cross-sectional, elevational, exploded view of an exemplaryprojection screen 100 in accordance with another alternative embodimentof the present invention. The projection screen 100 includes a substrate101, two adhesive layers 103, 104, a reflective layer 106, and adiffusion layer 108. The substrate 101 is preferably flexible andconstructed from polyvinylchloride (PVC) or some other comparablesubstrate material. The substrate 101 has a thickness preferably in therange of approximately five (5) mils to approximately eight (8) mils.The thickness of the substrate 101 is dictated by parameters such asstrength requirements for a given size of the projection screen 100, theenvironment in which the projection screen 100 will be used, and thedesired flexibility of the projection screen 100. Similar to thesubstrates 15, 45 of FIGS. 1-4, the substrate 101 of FIG. 6 defines aforward-facing or front surface 110. The substrate 101 may also definean opposed rear surface 120 that may be optionally secured by anyconventional method to a rigid substrate depending on the desired use ofthe projection screen 100.

The reflective layer 106 is preferably substantially identical toreflective layer 20 disclosed above with respect to FIG. 1. Accordingly,the reflective layer 106 preferably comprises a metallic film, such as afilm or foil of aluminum, and has a thickness in the range ofapproximately ⅓ mil to one (1) mil. When commercial grade aluminum foilis used as the reflective layer 106, such foil typically includes twoopposed surfaces 112, 114 having different reflectivity characteristics.For example, as noted above with respect to reflective layer 20, onesurface of the reflective layer 106 may have a high polished mirrorfinish and the other surface may have a matte finish. Depending on thedesired brightness of the image displayed on the projection screen 100,a surface with either finish may serve as the front surface 114 and beattached to the diffusion layer 108 as discussed in more detail below.For example, when a brighter image is desired, the surface of thereflective material having the greater reflectivity is used as the frontsurface 114 of the reflective layer 106. On the other hand, when aduller image is desired, the surface of the reflective material havingthe lesser reflectivity is used as the front surface 1 14 of thereflective layer 106.

The diffusion layer 108 is preferably substantially identical todiffusion layer 30 of FIG. 1 and, therefore, is preferably fabricatedfrom a resin, such as polypropylene or polyethylene. The thickness ofthe diffusion layer 108 is greater than one (1) mil and is preferably inthe range of approximately two (2) mils to eight (8) mils, as is thethickness of diffusion layer 30 disclosed above. The diffusion layer 108includes a front surface 118 and an opposed rear surface 116. The frontsurface 118 of the diffusion layer 108 preferably includes a pluralityof irregularities, such as those used to form a matte finish asillustrated in exemplary form in FIG. 7. The matte finish or otherirregularities may be fabricated using a press roller or any otherconventional technique. The rear surface 116 of the diffusion layer 108preferably includes a substantially smooth finish, but may alternativelyinclude a matte or other finish, or other irregularities, depending onthe desired diffusion characteristics of the diffusion layer 108.

The adhesive layers 103, 104 are preferably very thin (e.g., in therange of about ¼ to ½ mil) and are fabricated from acommercially-available optically transparent adhesive. In alternativeembodiments, different adhesives in different thicknesses may be usedfor the adhesive layers 103, 104; however, use of an opticallytransparent adhesive is preferred for adhesive layer 104. Adhesive layer103 functions to attach the front surface 110 of the substrate 101 tothe rear surface 112 of the reflective layer 106. Adhesive layer 104functions to attach the front surface 114 of the reflective layer 106 tothe rear surface 112 of the diffusion layer 108. Reflective layer 106may alternatively be applied to the rear surface 116 of the diffusionlayer 108 and/or to the front surface 110 of the substrate 101 by vacuummetalization or other conventional techniques, instead of usingadhesives. In such a case, the adhesive layers 103, 104 would not beused to form the projection screen 100.

When constructed with the substrate 101, the reflective layer 106, thediffusion layer 108 and the adhesive layers 103, 104 as described above,the projection screen 100 has a thickness preferably in the range ofapproximately eight mils (8) to approximately twenty (20) mils. Inaddition, when so constructed, the projection screen 100 is sufficientlyflexible to enable it to be wound around a roller during periods ofnon-use and then expanded during periods of use. Moreover, as confirmedthrough experiments conducted on the above-described projection screen100, use of a matte finish on the front surface 118 of the diffusionlayer 108 causes the directivity along a vertical axis relative to anormal line passing perpendicularly through a center of the projectionscreen 100 to be substantially the same as the directivity along ahorizontal axis relative to such normal line, thereby providing enhanceddirectionality as compared to prior art screens.

FIG. 8 is a perspective view of a projection screen system 200 inaccordance with a further alternative embodiment of the presentinvention. As depicted, the projection screen system 200 preferablyincludes the above-described projection screen 100, a roller 201, and anoptional bar or tube 203. The roller 201 and optional bar 203 areconventional devices used in various commercially available frontprojection screens, such as the “Lectric I” projection screen which isavailable from Vutec Corporation of Pompano Beach, Fla. The bar 203 maybe used to aid in raising and lowering, or more generally opening andclosing, the projection screen 100, and may include an attached handle(not shown). In the system 200 depicted in FIG. 2, the projection screen100 is wound around the roller 201 for storage when the projectionscreen 100 is not in use. In such system 200, the rear surface 120 ofthe substrate 101 is preferably adjacent the roller 201 when theprojection screen 100 is wound around the roller 201, thereby preventingthe viewing surface 118 of the screen 100 from contacting the roller 201when the projection screen 100 is closed and stored. The projectionsystem 200 may form part of a fixed system (e.g., in a conference roomor classroom) or may comprise part of a portable system as desired bythe user.

Various modifications and alterations of this invention will becomeapparent to those skilled in the art without departing from the scopeand spirit of this invention, and it is understood that this inventionis not limited to the illustrative embodiments set forth hereinbefore.

1. A projection screen comprising: a substrate; a reflective layerhaving a first surface and an opposing second surface, the secondsurface of the reflective layer being attached to the substrate, thefirst surface of the reflective layer having an unpolished finish; and adiffusion layer attached to the first surface of the reflective layer.2. The projection screen of claim 1, wherein the reflective layercomprises aluminum.
 3. The projection screen of claim 1, wherein thefirst surface of the reflective layer has a matte finish.
 4. Theprojection screen of claim 1, wherein the second surface of thereflective layer has a polished finish.
 5. The projection screen ofclaim 1, wherein the diffusion layer is a resin.
 6. The projectionscreen of claim 5, wherein the resin is one of polyethylene andpolypropylene.
 7. The projection screen of claim 1, further comprisingan optically transparent adhesive that attaches the diffusion layer tothe first surface of the reflective layer.
 8. The projection screen ofclaim 1, further comprising an adhesive that attaches the first surfaceof the substrate to the second surface of the reflective layer.
 9. Theprojection screen of claim 1, wherein the diffusion layer has athickness greater than one one-thousandth of an inch (one mil).
 10. Theprojection screen of claim 9, wherein the thickness of the diffusionlayer is in the range of approximately two mils to approximately eightmils.
 11. The projection screen of claim 1, wherein the substratecomprises polyvinylchloride and has a thickness in the range ofapproximately five mils to approximately eight mils.
 12. The projectionscreen of claim 1, wherein the reflective layer has a thickness in therange of approximately one-third of a mil to approximately one mil. 13.The projection screen of claim 1, wherein the substrate, the reflectivelayer and the diffusion layer are sufficiently flexible to enable theprojection screen to be wound around a roller during periods of non-use.14. The projection screen of claim 1, wherein the diffusion layerincludes a first surface and an opposing second surface, the secondsurface of the diffusion layer being attached to the first surface ofthe reflective layer, at least the first surface of the diffusion layerincluding a plurality of irregularities.
 15. The projection screen ofclaim 14, wherein the plurality of irregularities comprises a pluralityof micro lenses.
 16. The projection screen of claim 14, whereinplurality of irregularities constitute a matte finish.
 17. A projectionscreen system comprising: a projection screen that includes: asubstrate; a reflective layer having a first surface and an opposingsecond surface, the second surface of the reflective layer beingattached to the substrate, the first surface of the reflective layerhaving an unpolished finish; and a diffusion layer attached to the firstsurface of the reflective layer; and a roller around which theprojection screen is wound when the projection screen is not in use. 18.The projection screen system of claim 17, wherein the first surface ofthe reflective layer has a matte finish.
 19. The projection screensystem of claim 17, wherein the diffusion layer includes a first surfaceand an opposing second surface, the second surface of the diffusionlayer being attached to the first surface of the reflective layer, atleast the first surface of the diffusion layer including a plurality ofirregularities.
 20. A projection screen comprising: a substrate; areflective layer having a first surface and an opposing second surface,the second surface of the reflective layer being attached to thesubstrate, the first surface of the reflective layer having anunpolished finish; a diffusion layer coupled to the reflective layersuch that the reflective layer is positioned between the substrate andthe diffusion layer, the diffusion layer including a plurality ofirregularities to achieve a desired directivity.
 21. The projectionscreen of claim 20, wherein the first surface of the reflective layerhas a matte finish.
 22. The projection screen of claim 20, wherein theplurality of irregularities comprises a plurality of micro lenses. 23.The projection screen of claim 20, wherein the second surface of thereflective layer has a polished finish.
 24. The projection screen ofclaim 20, wherein the diffusion layer has a thickness greater than oneone-thousandth of an inch (one mil).